This invention relates to a method for the production of a food acid and to a food acid produced in accordance with the method.
U.S. Pat. No. 3,506,453 describes agglomerated fumaric acid compositions prepared by mixing finely divided components with just enough liquid to cause the component surfaces to become tacky. The components are then contracted with humid air stream and the components agglomerate to form a porous agglomerated product.
According to a first aspect of the invention there is provided a method for the production of a food acid, the method including the steps of combining fumaric acid with an organic acidic material selected from malic acid, tartaric acid, citric acid, lactic acid, ascorbic acid and mixtures of any two or more thereof in an aqueous medium to produce a mixture; and drying the mixture to produce a food acid comprising a particulate material containing fumaric acid and the organic acidic material, the quantity of fumaric acid and the quantities of the organic acidic material being selected so that the fumaric acid makes up between 5% and 95% of the particulate material, the combining step being selected from one of admixing finely divided fumaric acid with an aqueous solution of the organic acidic material; grinding the fumaric acid in the presence of an aqueous solution of the organic acidic material to produce slurry; and grinding the fumaric acid in an aqueous medium to produce a milled fumaric acid slurry and then adding the organic acidic material to the milled fumaric acid slurry.
The percentage compositions given in this specification refer to percentage compositions by mass.
Preferably, the quantity of fumaric acid and the quantity of the organic acidic material will be selected so that the fumaric acid makes up between about 40 and 60% of the particulate material, and more preferably between about 45 and 55%.
The fumaric acid may be cold water soluble (or CWS) fumaric acid. Cold water soluble fumaric acid refers to finely ground fumaric acid which includes a small amount of a wetting agent of the type marketed as CWS fumaric acid by Haarmann and Reimer or a granular fumaric acid material of the type marketed by NCP Food Products as granular cold water soluble fumaric acid.
The organic acidic material may be selected from malic acid, tartaric acid, citric acid, lactic acid, ascorbic acid and mixtures of any two or more thereof. Preferably the organic acidic material will be a mixture of malic acid and tartaric acid. The organic acids are thus water-soluble edible acids i.e. acids permitted in foods.
The quantity of malic acid may be selected so that the malic acid makes up about 40-60% of the particulate material and preferably about 50%. The quantity of tartaric acid may be selected so that the tartaric acid makes up about 3-10% of the particulate material and preferably about 5%.
The method may thus involve admixing finely divided fumaric acid with an aqueous solution of malic acid and tartaric acid. The admixing step may include grinding the fumaric acid in the presence of the aqueous solution of the malic acid and tartaric acid to provide the slurry or grinding the fumaric acid in the aqueous medium and then adding or blending the malic acid and tartaric acid into the milled fumaric acid slurry or spraying an aqueous solution of malic acid and tartaric acid, or spraying separate solutions of malic acid and tartaric acid, onto fumaric acid in powder form.
Thus the combining step may include admixing finely divided fumaric acid with an aqueous solution of malic acid and tartaric acid. Instead, the combining step may include grinding the fumaric acid in the presence of an aqueous solution of malic acid and tartaric acid to produce a slurry. Instead, the combining step may include grinding the fumaric acid in an aqueous medium to produce a milled fumaric acid slurry and then adding or blending the malic acid and tartaric acid into the milled fumaric acid slurry. Instead, the combining step may include spraying an aqueous solution of malic acid and tartaric acid onto fumaric acid in powdered form. Instead, the combining step may include spraying separate aqueous solutions of malic acid and tartaric acid onto fumaric acid in powder form.
The grinding step may be conducted in a wet mill so that the mixture is in the form of a slurry in which the particle size of essentially all the solid material in the slurry is not greater than 150 microns (100 mesh) and the average particle size is between about 100 and 25 microns (150-500 mesh). Preferably, the grinding step is conducted so that the particle size of essentially all of the solid material in the slurry is not greater than 100 microns (150 mesh) and the average particle size is between about 75 and 25 microns (200-500 mesh).
The drying step may include spray drying or spray granulating the slurry. Thus the drying step may be selected from spray drying and spray granulating. In particular, the drying step may be a spray granulating step which is conducted in a fluid bed granulator by a continuous or a batch process to give a free-flowing non-dusting product. The spray granulation step may be controlled such that granules of 20-60 mesh, preferably 30-45 mesh are produced directly, or are selected from the product by screening, with the rejected material being reprocessed.
The final particle size is typically controlled by screening or sifting, to remove oversize particles which are then ground finely in a mill and returned to the fluidized bed of the granulator. Undersized particles are also removed by screening or sifting and are then returned to the fluidized bed. Further, when the drying step is conducted by a continuous process, a certain amount of material segregation of the particles takes place as the smaller particles are lifted higher and tend to come into contact with more of the fresh solution/slurry being sprayed into the bed, and consequently grow in preference to the larger particles which remain in the lower reaches of the bed. The overflow of the bed is generally situated near the bottom of the bed to remove the larger particles. In this way, the final particle size is controlled between about 20 and 100 mesh (840-150 microns) and ideally between about 24 and 60 mesh (700-250 microns).
The particulate material may, after the spray granulation step, be dried to a moisture level of less than 0,5% and preferably less than 0,25%.
Thus, the mixture may be dried to produce a particulate material having a moisture level of less than 0,5%, and preferably less than 0,25%.
The combining step may be conducted in the presence of a wetting agent or surfactant. The wetting agent may, for example, be dissolved in the aqueous medium so that the particulate material which is produced is uniformly mixed with the wetting agent. The admixing step may, further, be conducted in the presence of an anti-foaming agent. The anti-foaming agent may also be dissolved in the aqueous solution.
The wetting agent may be a liquid wetting agent. Such a liquid wetting agent will typically be edible and essentially tasteless. It may, for example, be a liquid alkyl sulphosuccinate such as dioctyl sodium sulphosuccinate, sodium lauryl sulphate, Tween (trade name) or any other suitable edible wetting agent or surfactant. The anti-foaming agent may be a silicone anti-foaming agent. It may, for example, be a food grade silicone oil anti-foaming agent.
The quantity of the wetting agent may be selected so that it comprises about 0,1-0,5% of the final product i.e. of the food acid. The quantity of the anti-foaming agent may be selected so that it controls foam during he admixing and drying steps and comprises about 2-20 ppm preferably about 5-15 ppm and most preferably about 10 ppm of the final product i.e. of the food acid.
The method may include the further step of incorporating an additive selected from flavourants, colourants, sweeteners and mixtures of two or more thereof in the food acid. Typically the additive will be sprayed onto the mixture during the spray-drying or spray-granulating step.
The invention extends to a food acid in particulate form produced by a method as hereinbefore described.
The invention extends further to a food acid in particulate form, the food acid comprising a composite material which includes fumaric acid in an amount of about 5%-95%, malic acid in an amount of about 5-95% and tartaric acid in an amount of about 3-15%.